Diene rubbers such as natural rubber, isoprene rubber, SBR or BR have wide applications in tires, automotive parts and industrial parts, because of excellent characteristics such as workability, strength and the like. These diene rubbers, however, are poor in weatherability and ozone resistance, and also do not have sufficient damping properties and vibration-insulating properties, and hence further improvements have been desired from the viewpoint of the practical use.
Ethylene/.alpha.-olefin copolymers represented by ethylene/propylene/diene copolymers have wide applications in automotive parts, industrial rubber parts, electrical insulating materials, and materials for civil engineering and construction. The ethylene/.alpha.-olefin copolymers, however, are poor in damping properties, vibration-insulating properties and dynamic fatigue resistance (flexual fatigue resistance), and hence there is room for further improvement in specific applications such as rubber vibration insulators, rubber rolls, belts and tires.
Further, nitrile rubbers and hydrogenated nitrile rubbers have also wide applications such as sealants, hoses and belts because of being excellent in characteristics such as strength and oil resistance. The nitrile rubbers and hydrogenated nitrile rubbers, however, are poor in weatherability, ozone resistance, low temperature characteristics and dynamic fatigue resistance, and hence further improvement in these characteristics is desired.
U.S. Pat. No. 4,645,793 discloses a blend of a diene rubber and an ethylene/.alpha.-olefin copolymer rubber having improved weatherability and ozone resistance. However, drawbacks to such a blend include decrease in dynamic fatigue resistance (flexual fatigue resistance) and lowering in adhesive power to fiber.
Further, Journal of the Japan Rubber Association, 49, 236, 241, 246 (1976) discloses a blend of an ethylene/.alpha.-olefin copolymer rubber having improved weatherability and ozone resistance. However, such a blend has also drawbacks including decrease in dynamic fatigue resistance (flexual fatigue resistance) and lowering in adhesive power to fiber.
Therefore, there has long been desired vulcanizable rubber compositions excellent in workability, strength characteristics, weatherability, ozone resistance and dynamic fatigue resistance, as well as excellent in vibration-insulating properties, damping properties and adhesive properties to fiber.
The present inventors have found that the above-mentioned drawbacks can be solved by a composition comprising a higher .alpha.-olefin copolymer (1) obtained by copolymerization in the presence of a specific olefin polymerization catalyst of a specific higher .alpha.-olefin, a specific .alpha., .omega.-diene and a specific non-conjugated diene, and a rubber (2) selected from the group consisting of a diene rubber, an ethylene/.alpha.-olefin copolymer, a nitrile rubber and a hydrogenated nitrile rubber.